Parachutes are a good way to learn about physics and aerodynamics. They are also fairly easy to make with the right materials. The materials can be made out of plastic bags, nylon fabrics from discarded tents, strings and an object that will serve as the payload.
The instructions are very easy and there many resources that you can find in the internet. This is why parachutes are common science projects.
There are many variations that can be done with a parachute.

You can make different designs and make a few variations with your over all design to yield different results.
Parachute Projects
Parachutes work by slowing down the descent of a person or object in the atmosphere. They create drag or air resistance that slows down the descent while being pulled down by gravity. You can experiment with different designs but the easiest to make would be round shaped parachutes.
When an object falls down it has to push air molecules away.

This causes the drag or air resistance that inflates parachutes. The amount of drag can be measured through the cross sectional area of the object. The canopy of a parachute has a large cross sectional area which results to more drag. This is what makes the falling object with a parachute slow down.
To be able to make a falling object have a soft landing, it must reach a terminal velocity. This is accomplished when the weight of the object is equal to the drag or air resistance. To be able to get the right drag you must have a chute with the right size. The size of the chute will depend on the payload or your weight. Generally, heavier objects need canopies with bigger radius. There is a formula for a decent speed for payloads that is applied to round parachutes.

The best way to start is to go simple first so that you will have an idea on how it works. Then you can go from there and experiment with different materials and weights. Using sand can be a bit hard to gauge. You can opt to go for large canopies if you want to try heavier weights. There are materials that are air resistant while some are not. Most if the time it will depend on the weight of your materials.
Toy parachutes can be made from plastic bags and strings. Apart from plastic bags you can also use a bandanna, handkerchief, scarf or any lightweight fabric. If fabrics are not available use lightweight paper. You can decide on what object you are going to use for the payload.

The simplest payload would be metal washers. It's preferable to use lightweight strings.
Make small overhand knots at the corners of your cloth. Then tie the string above the knots. Hold the center of your cloth and pull the strings. Tie the ends of your strings with an overhand knot. Lastly tie the strings to the metal washer. Release the parachute 6 feet high.
It's more convenient to use a lark's head knot so that you will able to easily untie your payload. You can add more metal washers if you want to experiment.

You can also add suspension lines if you want a different design. There are also other materials that you can use. After you know the basics you can try out nylon fabrics from discarded tents and have heavier weights.
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